We often tend to make judgments without much reflection, without any true empathy, and those judgments can cause us to feel resentment towards the other, leading to anger. But if we hold off on the judgment, and seek instead to sincerely comprehend where the other is coming from, a completely different dynamic can be formed.
One can hardly avoid referring to the biblical admonition, "Judge not lest you be judged," and "Judgment is the Lord's." Only God can truly know a person's heart, and only God can make a true judgment. We humans, even with the best of empathy cannot, and so, while we may judge an action, objectively, to be right or wrong, we cannot safely judge motives. Often, the person him or herself, doesn't fully understand their own motives, how can another do so? So, we should stop judging, work to develop empathy, and things should be better for all involved!
The book is very good for those who want to understand anger in terms of how the brain works, and related techniques to control anger.